Fabrication of Cobalt Sulfide/Graphene Sheets Nanocomposite Harvesting Improved Anode Performance for Lithium-Ion Battery.

Abstract

A cobalt sulfide (CoS)/graphene sheets (GS) nanocomposite was successfully synthesized through a simple one-pot hydrothermal route assisted by ethylenediamine. The crystalline phase, structure and morphology of this nanocomposite were systematically characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen (N₂) absorption-desorption isotherm, Raman spectroscopy and thermogravimetric analysis (TGA). The results revealed that the CoS nanoparticles with size distribution of 30-100 nm were highly dispersed on or well anchored in the creasy GS substrate. Integrating nanosized CoS compound and GS outstanding merits, the as-obtained CoS/GS nanocomposite as an anode material for lithiumion battery exhibited high reversible capacity, excellent long-cycle stability and remarkable high-rate capability, which were all superior to those of pristine CoS. Moreover, this nanocomposite maintained a high capacity of ˜600 mAh·g-1 after 200 cycles at a current density of 100 mA·g-1. The approach presented in this work is readily applicable to nanoparticle decoration of graphene sheets and preparation of other graphene-based nanocomposites as anode materials for lithium-ion batteries.